-18x2 -20x -2 = 0
ax2 bx c = 0
a = -18
b = -20
c = -2
Δ = b2-4ac
Δ = -20² - (4 * -18 * -2)
Δ = 400 - (4*36)
Δ = 400 - (144)
Δ = 256 Δ > 0
-18x2-20x-2=0
x = -b ∓ √Δ 2a
x' = 20 - √256 2*-18 = 20 - 16.0 -36 = 4.0 -36 = -0.111111111111
x" = 20 + √256 2*-18 = 20 + 16.0 -36 = 36.0 -36 = -1.0
x' = -36.0
x" = -324.0
S = {x ∈ R / x' = -36.0, x" = -324.0 }